Device

Advantages

Disadvantages

Inexpensive, readily available, compact.

Averaging device, easily damaged by external magnetic fields, does not indicate magnetic field strength.

Inexpensive, easy to use.

Averaging device, can easily damage magnet under test, test results can be confusing, does not indicate magentic field strength.

Expensive, requires knowledge of electromagnetism.

Difficult to obtain for this application.  Inaccurate and cumbersome to use.

Extremely accurate, available from a variety of suppliers, indicates both pole polarity and field strength.

Expensive.

Accurate, compact, easy to use, measures both polarity and minimum strength of magnets, no averaging, will not harm device under test, inexpensive and cannot be damaged by strong magnetic fields.

Does not indicate exact field density.